Since the 1940""s most napkin folders were based on the methods and apparatus taught by Christman in U.S. Pat. No. 1,974,149 to make single transverse folded napkins.
This basic prior art (see FIG. 1) is typical for vacuum folders and is still practiced in present apparatus, including those with an additional roll to produce double folded dinner napkins like the apparatus of Nystrand in U.S. Pat. No. 3,689,061 (FIG. 1) U.S. Pat. No. 3,870,292 of Bradley (FIG. 3).
Folders with the three roll arrangement of FIG. 1 convert parent rolls of paper or other material into single transversely folded products from one or more juxtaposed webs by longitudional and cross folding before packout into one or more delivery lanes.
By using different longitudinal folding plates and re-sizing folding rolls, dispenser and other types of folded napkins are made using the basic idea of lifting the front panel portion with a coacting vacuum roll while the trailing panel portion is advanced by a carrier until release of the first panel to complete the fold.
To double production, two folders are arranged as in FIG. 2 to deliver a pair of superposed napkins which are packed out in pairs.
In the single or dual folder arrangements, all napkins in all delivery lanes are produced from the same parent roll and are thus of the same color or material.
U.S. Pat. No. 5,904,277 describes a transverse folder using an air blast to uplift the leading panel portion while the trailing portion is held on a carrier. The uplifted front portion subsequently contacts a stationary plate to complete the fold.
The instant apparatus uses the air blast/plate folding techniques of ""277 as well as components in various combinations for internal air and vacuum conduits according to U.S. application Ser. No. 481,108.
Without requiring a coacting vacuum folding roll to complete a fold, apparatus of this invention includes a hollow carrier cylinder with internal vacuum and air conduits.
While hollow rolls are preferred, this invention can be practiced using solid rolls with holes drilled parallel to the axis of rotation for use as closed vacuum conduits.
For wider webs, larger diameter cylinders are used to minimize deflection, and beneficially provide more circumferential space to mount two or more segment cutoff units required to practice this invention.
By slow speed advancement of the incoming webs and slipping them one or more repeats on the surface of the anvil roll(s), a segment from each co-acting cutoff unit is advanced at full speed after cutoff occurs, with each anvil roll synchronized to place a segment on spaced repeats on the surface of a single common multi-repeat carrier cylinder.
when using two feed and cutoff units to advance two webs, the speed of each web is reduced to one-half of folder surface speed.
With three units, the speed of each web would be one third of folder speed.
Reduced web speeds results in longer parent roll run time between roll changes.
With hollow cylinders instead of solid rolls, wider machines become practical, and width of the inventive folders can be increased to handle parent rolls of 100xe2x80x3.
For example, with the inventive apparatus using only white paper, a 200xe2x80x3 parent roll can be slit in half. One web is processed in-line, and the other 100xe2x80x3 web is advanced over two turning bars and superposed with the in-line web.
When paper machine widths approach 100xe2x80x3, excessive deflection of the cutoff rolls can affect folder cutting quality and efficiency.
To overcome this problem, the invention describes a special cutaway central intermediate framework for using two circumferentially spaced cutoff units which are phased and synchronized to cut segments from product width webs slit from each half width parent roll web.
Use of the central cutaway frame for mounting partial width cutoff units also applies to the face-to-face arrangement of dual folders, each of which process two 100xe2x80x3 webs, or using a plurality of cutoff units, two 200xe2x80x3 parent rolls slit into four half width webs.
The use of two or more cutoff units in combination with slow speed web feed means defines different color and material delivery sequences heretofore not possible.
This invention also describes the use of multiple locations for removel of product and delivery of stacks. Each delivery system at a different location must accept product from the carrier at the folder production rate, but with separate delivery apparatus, digital switching of vacuum can produce different package counts at each location with more time for package count separation, stacking, and advancement to packaging machines.
In summary, the primary object of the invention is to provide apparatus for producing stacks having folded product of different colors, materials, or counts. all in a variety of sequences.
Another object is to provide different apparatus arrangements for producing more than one color sequence.
A further object of this invention is to feed multiple webs at speeds lower than the folder speed so that parent rolls last longer.
An object of this invention is to provide apparatus for rotation of parent rolls on an axis parallel to the carrier axis to present a juxtaposed plurality of longitudinally folded webs for ease of manual threadup into draw rolls.
Another object is to provide a pivotable S-wrap roll and coacting metering roll combination having an open upward facing nip for manual threadup from the top before pivoting the S-wrap roll into a run position.
An object of this invention is to provide a partial central framework to mount half width feed/cutoff units for synchronized cutting of longitudinally folded webs having a combined width equal to the width all incoming product web widths.
An object of the invention is to slit webs wider than the folder width and provide means to redirect a second half web to an in-line run direction superposed over the first half width web.
An object of the invention is to provide means for multiple product removal locations.
Another object is to electronically activate means for controlling the number and removal of different count at each of the multiple removal locations.
Other advantages and objects of the invention may be seen in the details of the ensuing specification.